source: trunk/server/source3/lib/addrchange.c

/*
 * Samba Unix/Linux SMB client library
 * Copyright (C) Volker Lendecke 2011
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "includes.h"
#include "lib/addrchange.h"
#include "../lib/util/tevent_ntstatus.h"

#if HAVE_LINUX_RTNETLINK_H

#include "asm/types.h"
#include "linux/netlink.h"
#include "linux/rtnetlink.h"
#include "lib/async_req/async_sock.h"

struct addrchange_context {
        int sock;
};

static int addrchange_context_destructor(struct addrchange_context *c);

NTSTATUS addrchange_context_create(TALLOC_CTX *mem_ctx,
                                   struct addrchange_context **pctx)
{
        struct addrchange_context *ctx;
        struct sockaddr_nl addr;
        NTSTATUS status;
        int res;

        ctx = talloc(mem_ctx, struct addrchange_context);
        if (ctx == NULL) {
                return NT_STATUS_NO_MEMORY;
        }

        ctx->sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
        if (ctx->sock == -1) {
                status = map_nt_error_from_unix(errno);
                goto fail;
        }
        talloc_set_destructor(ctx, addrchange_context_destructor);

        /*
         * We're interested in address changes
         */
        ZERO_STRUCT(addr);
        addr.nl_family = AF_NETLINK;
        addr.nl_groups = RTMGRP_IPV6_IFADDR | RTMGRP_IPV4_IFADDR;

        res = bind(ctx->sock, (struct sockaddr *)(void *)&addr, sizeof(addr));
        if (res == -1) {
                status = map_nt_error_from_unix(errno);
                goto fail;
        }

        *pctx = ctx;
        return NT_STATUS_OK;
fail:
        TALLOC_FREE(ctx);
        return status;
}

static int addrchange_context_destructor(struct addrchange_context *c)
{
        if (c->sock != -1) {
                close(c->sock);
                c->sock = -1;
        }
        return 0;
}

struct addrchange_state {
        struct tevent_context *ev;
        struct addrchange_context *ctx;
        uint8_t buf[8192];
        struct sockaddr_storage fromaddr;
        socklen_t fromaddr_len;

        enum addrchange_type type;
        struct sockaddr_storage addr;
};

static void addrchange_done(struct tevent_req *subreq);

struct tevent_req *addrchange_send(TALLOC_CTX *mem_ctx,
                                   struct tevent_context *ev,
                                   struct addrchange_context *ctx)
{
        struct tevent_req *req, *subreq;
        struct addrchange_state *state;

        req = tevent_req_create(mem_ctx, &state, struct addrchange_state);
        if (req == NULL) {
                return NULL;
        }
        state->ev = ev;
        state->ctx = ctx;

        state->fromaddr_len = sizeof(state->fromaddr);
        subreq = recvfrom_send(state, state->ev, state->ctx->sock,
                               state->buf, sizeof(state->buf), 0,
                               &state->fromaddr, &state->fromaddr_len);
        if (tevent_req_nomem(subreq, req)) {
                return tevent_req_post(req, state->ev);
        }
        tevent_req_set_callback(subreq, addrchange_done, req);
        return req;
}

static void addrchange_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct addrchange_state *state = tevent_req_data(
                req, struct addrchange_state);
        struct sockaddr_nl *addr;
        struct nlmsghdr *h;
        struct ifaddrmsg *ifa;
        struct rtattr *rta;
        ssize_t received;
        int len;
        int err;
        bool found;

        received = recvfrom_recv(subreq, &err);
        TALLOC_FREE(subreq);
        if (received == -1) {
                DEBUG(10, ("recvfrom returned %s\n", strerror(errno)));
                tevent_req_nterror(req, map_nt_error_from_unix(err));
                return;
        }
        if ((state->fromaddr_len != sizeof(struct sockaddr_nl))
            || (state->fromaddr.ss_family != AF_NETLINK)) {
                DEBUG(10, ("Got message from wrong addr\n"));
                goto retry;
        }

        addr = (struct sockaddr_nl *)(void *)&state->addr;
        if (addr->nl_pid != 0) {
                DEBUG(10, ("Got msg from pid %d, not from the kernel\n",
                           (int)addr->nl_pid));
                goto retry;
        }

        if (received < sizeof(struct nlmsghdr)) {
                DEBUG(10, ("received %d, expected at least %d\n",
                           (int)received, (int)sizeof(struct nlmsghdr)));
                goto retry;
        }

        h = (struct nlmsghdr *)state->buf;
        if (h->nlmsg_len < sizeof(struct nlmsghdr)) {
                DEBUG(10, ("nlmsg_len=%d, expected at least %d\n",
                           (int)h->nlmsg_len, (int)sizeof(struct nlmsghdr)));
                goto retry;
        }
        if (h->nlmsg_len > received) {
                DEBUG(10, ("nlmsg_len=%d, expected at most %d\n",
                           (int)h->nlmsg_len, (int)received));
                goto retry;
        }
        switch (h->nlmsg_type) {
        case RTM_NEWADDR:
                state->type = ADDRCHANGE_ADD;
                break;
        case RTM_DELADDR:
                state->type = ADDRCHANGE_DEL;
                break;
        default:
                DEBUG(10, ("Got unexpected type %d - ignoring\n", h->nlmsg_type));
                goto retry;
        }

        if (h->nlmsg_len < sizeof(struct nlmsghdr)+sizeof(struct ifaddrmsg)) {
                DEBUG(10, ("nlmsg_len=%d, expected at least %d\n",
                           (int)h->nlmsg_len,
                           (int)(sizeof(struct nlmsghdr)
                                 +sizeof(struct ifaddrmsg))));
                tevent_req_nterror(req, NT_STATUS_UNEXPECTED_IO_ERROR);
                return;
        }

        ifa = (struct ifaddrmsg *)NLMSG_DATA(h);

        state->addr.ss_family = ifa->ifa_family;

        rta = IFA_RTA(ifa);
        len = h->nlmsg_len - sizeof(struct nlmsghdr) + sizeof(struct ifaddrmsg);

        found = false;

        for (rta = IFA_RTA(ifa); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {

                if ((rta->rta_type != IFA_LOCAL)
                    && (rta->rta_type != IFA_ADDRESS)) {
                        continue;
                }

                switch (ifa->ifa_family) {
                case AF_INET: {
                        struct sockaddr_in *v4_addr;
                        v4_addr = (struct sockaddr_in *)(void *)&state->addr;

                        if (RTA_PAYLOAD(rta) != sizeof(uint32_t)) {
                                continue;
                        }
                        v4_addr->sin_addr.s_addr = *(uint32_t *)RTA_DATA(rta);
                        found = true;
                        break;
                }
                case AF_INET6: {
                        struct sockaddr_in6 *v6_addr;
                        v6_addr = (struct sockaddr_in6 *)(void *)&state->addr;

                        if (RTA_PAYLOAD(rta) !=
                            sizeof(v6_addr->sin6_addr.s6_addr)) {
                                continue;
                        }
                        memcpy(v6_addr->sin6_addr.s6_addr, RTA_DATA(rta),
                               sizeof(v6_addr->sin6_addr.s6_addr));
                        found = true;
                        break;
                }
                }
        }

        if (!found) {
                tevent_req_nterror(req, NT_STATUS_INVALID_ADDRESS);
                return;
        }

        tevent_req_done(req);
        return;

retry:
        state->fromaddr_len = sizeof(state->fromaddr);
        subreq = recvfrom_send(state, state->ev, state->ctx->sock,
                               state->buf, sizeof(state->buf), 0,
                               &state->fromaddr, &state->fromaddr_len);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, addrchange_done, req);
}

NTSTATUS addrchange_recv(struct tevent_req *req, enum addrchange_type *type,
                         struct sockaddr_storage *addr)
{
        struct addrchange_state *state = tevent_req_data(
                req, struct addrchange_state);
        NTSTATUS status;

        if (tevent_req_is_nterror(req, &status)) {
                return status;
        }

        *type = state->type;
        *addr = state->addr;
        return NT_STATUS_OK;
}

#else

NTSTATUS addrchange_context_create(TALLOC_CTX *mem_ctx,
                                   struct addrchange_context **pctx)
{
        return NT_STATUS_NOT_SUPPORTED;
}

struct tevent_req *addrchange_send(TALLOC_CTX *mem_ctx,
                                   struct tevent_context *ev,
                                   struct addrchange_context *ctx)
{
        return NULL;
}

NTSTATUS addrchange_recv(struct tevent_req *req, enum addrchange_type *type,
                         struct sockaddr_storage *addr)
{
        return NT_STATUS_NOT_IMPLEMENTED;
}

#endif